Testing apparatus



TESTING APPARATUS March 9, 1943. J. L. BRUBAKER Em 2,313,516

Filed July 27, 1940 Sheets-Sheet 1 wvmrans 1 1. BRUBA/l'E/P I: 1 if 1V6Vf/V/S 7 March 9 19.43".

J. L. BRUBAKER ETAL I TEST IN G APPARATUS Filed July 27, 1940 3Sheets-Sheet 2 March 9,1943.

J. 1.. BRUBAKER EI'AL TESTINGAPPARATUS I 3 Sheets-Sheet Filed July 27,1940 Patented Mar. 9, 1943 wane UNITED STATES PATENT ()FFICE TESTINGAPPARATUS Application July 27, 1940, Serial No. 347,926

8 Claims.

This invention relates to testing apparatus and more particularly toapparatus for indicating what two equal portions of a toroidal core haveequal magnetic reluctance,

In the manufacture of molybdenum Permalloy dust cores, which aretoroidal in shape and which are adapted particularly for use in loadingcoils of telephone systems, it is extremely diflicult to distribute themagnetic material in the core so as to obtain a core ring of uniformmagnetic properties. For this reason, two equal windings, woundsymmetrically on opposite portions of a core selected at random, willnot ordinarily have equal inductance and must be balanced by adding orremoving turns to equalize, insofar as possible, the inductance of thewindings.

t is an object of the present invention to provide apparatus fordetermining and indicating a characteristic of a core.

A further object is to provide apparatus for determining and indicatingwhich two equal portions of a ring-shaped core have substantially equalmagnetic reluctance.

In accordance with one embodiment of the invention, semi-circular splitcoils are provided within which a core ring may be positioned andmechanism is provided for rotating the core within the coils, whilemeasuring diametrically opposed halves of the core, to bring the core toa position where the split coils windings are influenced substantiallyequally by the core. An inductance unbalance bridge, including thesplitcoils, is utilized to determine the halves of the core which havesubstantially equal reluctance and means is provided for automaticallymarking the outside of the core with a mark to indicate a substantiallyneutral axis of the core. The mechanism for marking the core isautomatically controlled upon the opening of the split coils to permitremoval of the core from the apparatus.

A better understanding of the invention may be had by reference to thefollowing detailed description when considered in conjunction with theaccompanying drawings, wherein Fig. 1 is a side elevational view ofapparatus embodying the invention, the side plate of the box whichencloses part of a mechanism being removed to more clearly show theconstruction of the apparatus within the box;

Fig. 2 is a circuit diagram showing a suitable type inductance unbalancebridge for measuring the halves of the core to determine the point Wherethe split coils are substantially balanced inductively Fig. 3 is aVertical sectional view taken through the apparatus shown in Fig. 1 andshowing the details of the split coil and means for positioning the corewithin the coil; and

Fig, 4 is an enlarged plan view of the apparatus, parts being brokenaway to more clearly show the parts beneath them and showing the detailsof mechanism for automatically marl:- ing the neutral axis of the coreupon removal of the core from the split coil.

Referring to the drawings, wherein like reference characters designatethe same parts throughout the several views, the apparatus comprises, asshown in Fig. 1, a box-like struc-' ture Ill within which there ispositioned one turn II of the split coil and on top of which there ismounted the mechanism l2 for marking the neutral axis of the coil, andextending upwardly from which there is a guide I3 which carries theother portion M of the split coil. The box-like structure Ill comprisesa base member l5, an end member l6, and front and rear members I! and18, which support a top plate l9. Fixed to the base member I5 is thelower end of the guide l3 which extends upwardly from the base memherand through the top plate l9. The guide is comprises a channel member 23having a slot 24'formed in its web and having mounted on the ends of itsflanges a guide plate 25, which has a portion 26 extending into thechannel of the channel member 23 and which is fixed to the flanges ofthe member 23 by screws 21 21. The lower end or" the web of the channelmember 23 has 'a slot 28 formed in it through which extends an actuatingarm 29 fixed to a rack 39. The guide plate 25 does not extend throughoutthe end of the channel member 23, but terminates just below the topplate [9 to permit a gear segment 3| to engage its teeth with the teethof the rack 30. The gear segment Si is keyed to a shaft32, which is, inturn, journalled in bearing blocks 33, 34 and 36 secured to theunderside of the plate l9 by means of screws 35-35. The shaft 32carries, in addition to the gear segment 3i, a cam 31 and an actuatinghandle 38, which are fixed to the shaft 32.

Mounted on the rack 30, at its upper end, is an arm 59, which supportsthe portionl i of the split coil. A spider 5|, fixed to the end of thearm 50, has screwed thereto, by means of screws 52-52, aring 53 ofinsulating material. The ring 53 of insulating material has a pluralityof pockets 54 of relatively large diameter formed in it, whichcommunicate with apertures 55 of somewhat smaller diameter at the innerwall of the ring. Each of the pockets 54 has a shouldered member 55positioned in it with its shoulder engaging the shoulder formed by thejunction of the pocket 54 and the aperture 55 and with its reducedportion extending through the aperture 55. The end of each of thepockets 54 adjacent the periphery of the ring 53 has a retaining ring 51set into it, in which there is positioned a shoulder member 59 ofexactly the same construction as the shouldered member 56 and there ispositioned in each of the pockets 54 a compression spring 59, whichbears against the shouldered members 55 and 58 and urges them inwardlyand outwardly, respectively, so that the reduced portions of theshouldered members extend beyond the inner surface and outer surface ofthe ring 53 and are electrically interconnected by means of the springs59.

The top plate I9, which is made of insulating material, has superposedon it a rectangular block 65 of insulating material in which there isformed a circular aperture 65, which communicates with a similaraperture 91 in th top plate I9. Set into the edges of the apertures 56and 61 are a plurality of cont-actors 68, which, together with the upperedge of the aperture 66, are tapered, as shown at 69. Each of thesecont'actors 68 has extending downwardly from it and formed integrallywith it, a rod of conducting material which extend through holes 1Iformed in a tubular member 12 made of insulating material and having aninside diameter equal to the diameter of the apertures '55 and 61. Fixedto the bottom of. the

tubular member 12 (Fig. 3) is a disc 13, also made of insulatingmaterial and having attached to its lower edge a disc 14 of somewhatsmaller diameter. The disc 14 is grooved to receive connecting wires -15and has fixed to its lower faces a disc 16 of somewhat similarconstruction, which is also grooved to receive wires 15 and a third disc11 of the same diameter as the discs 14 and 15 is fixed to the undersideof the disc-1'6. An aperture 18 is formed centrally of the disc 11 andhas extending through it a bolt 19, on which there is threaded a nut 80for holding a sleeve 8I in position on the disc 11. The sleeve I? I" hasa series of grooves formed in its periphery to receive upwardlyextending portions of the Wires 15, which have-connected at their upperends contact members 82, which are, in turn, seated in slots 83 formedin the upper end of a sleeve 84' of insulating material, which surroundsthe sleeve 8!. The sleeve 84 is somewhat similar to the sleeve 81 inthat it has grooves in its periphery for receiving upwardly extendingportions of others of the wires 15 and in that it is encircled by stilla third sleeve 85, which is notched out at its upper end to receivecontacts 86 fixed to the upper ends lar shaped ring 90 of insulatingmaterial, which has a shoulder 9I extending outwardly over a ring 92,and which has a smaller shouldered portion 93 on which a loading coilcore 94 may be positioned to hold the core while it is being tested todetermine which two equal portions of it have equal magnetic quality.The ring 92 is fixed to the ends of a series of rods 95, which, at theirlower ends, are secured to a disc 96 of insulating material. Threadedinto the disc 96 is a shouldered pin 91, which extends through anaperture 99 in the actuating arm 29. The size of the ring 92 is suchthat it normally bears lightly againstthe inner wall of the aperture 66and tubul'ar member 12 so that when the actuating arm 29 starts to movedownwardly, the ring 92 will not immediately move with it, but after theactuating arm 29 moves down far enough for the edges of the aperture 98to engage the shoulder on the pin 91, the ring 92 will be drawndownwardly with the actuating arm 29 and since the irregularly shapedring 99 rests on the ring 92, it willalso move downwardly. Position-edwithin the tubular member 12, and rotatable about the sleeve 85, is aturn table H39- having a suitable abrasive on the upper face thereof.The turn table I09 is slightly less in diameter than the inside diameter of the ring 92 and when the ring 92 carries the ring 99 downwardlytothe point where the ring 90 will rest on the turn table I09, the turntable I00 will rotate the ring 90 with the core 94 on it. The turn tableI-00 has a groove I0 I- formed in its periphery for receiving a-beltI92, Which extends through holes inthe tubular member 12 and ispositioned about a sheave I03. The sheave I03 is fixed to a shaft I 94,which extends through the top plate I9 and has a dial or hand wheel I n5fixed to it, whereby rotation may be imparted to the turn table I00 uponrotation of the dial I95 to rotate the core 94 within the split coilformed of portions II and I 4.

Pivotally mounted on a pin IIO, which is secured to the top plate I9, isa lever I I I, whichcarries at its free end an actuating pin I I2, andwhich carries intermediate its ends a cam roller H3. The cam roller I I3is positioned in the path of the cam 31 and when the shaft 32 isrotated, the cam 31 will, through the cam roller II3, move the lever III downwardly, as viewed in Fig. 4, thereby to rock the lever III in acounter-clockwise direction about the pin III]. The actuating pin H2 issecured to a slidable block H4 and is slidable itself in a slot I I5 inthe lever I I I so that when the lever III is rocked in acounter-clockwise direction about the pin III), th block II 4 will bemoved downwardly (Fig. 4). The block of the shorter wires 15. There isthus provided a rigid stem or centerpiece having contacts 86 and 82positioned about its periphery at two different levels and connected towire 15, which, through the rods 19, are connected to contacts 68-.

From the foregoing, it is believed to be apparent that when the portionI4 of the split coil is moved downwardly to a position where the shoul-H4 is slidable within a framework H6 in which it is slidably mounted ona pair of guide members I I1 and I I8. The guide members I I1 and I I8are suitably fixed in the framework H6 and extend through holes H9 andI20, respectively, formed in the block II4. The framework H6 is mounted,by means of screws I2 II2 I, on the upper surface of the top plate I9and the block I I4 is urged toward the upper (Fig. 4) open end of theframework I I6 by a pair of compression springs I22 and I23, whichsurround pins I24 and I25, respectively, engaged in shouldered aperturesI29 and I21 in the block H4, the springs I22 and I23 engaging theshoulders I28 and I29, respectively, of the apertures I26 and I21.Mounted on the upper surface of the block I I4 is a plate I30 having anupwardly extending portion I.3I-, to which there is fixed a leaf springI32 for normally holding a plunger I33 of a solenoid I34 in the positionshown inFig. 4. The solenoid I34 is mounted on the plate I30 and uponenergization will draw the plunger I33upwardly (Fig. 4) to actuate arelatively soft marking element I35, which is mounted on an enlargedportion I36 of the stem I31 of the plunger I33. Also mounted on theplate I30 are a pair of spool supporting pins I38 and I39, on whichthere are rotatably mounted supply and takeupspools I40 and MI,respectively, for a typewriter ribbon I42. The supply spool I40 engagesits pin I38-frictionally and the ribbon I42 is directed from the spoolI40 over a guide roller I50, under a guide roller I5I,

across the end of the marking element I35, under a guide roller I52,over a guide roller 553, to the takeup spool I4I. A pin I5I rotatablysupports the guide roller I50 on the plate I30 and also supports a leverI32, which is urged to rock about the pin I5I in a counter-clockwisedirection by a coil spring I63, and which carries on its free end theguide roller I5I. In a similar manner, a pin I34 which rotatablysupports the guide roller I53, also rotatably supports a lever I35,which is urged to rock about the pin I94 by a spring I96 and whichcarries at its free end the guide roller I52. In this manner, the ribbonextending between the supply and takeup spools I40 and MI is held byspring tension against the marking elementI35, but may be moved upwardly(Fig. 4) upon energization of the solenoid I34.

Oscillatable about the pin I39 is a pawlsupporting lever I10, which isnormally urged downwardly (Fig. 4) into engagement with a pin I1I by acoiled spring I12. The lever I carries, at

its free end, a pawl I13, which is urged downwardly (Fig. 4) by a springI14interconnecting the pawl I13 and the lever I10. The pawl I13registers with the teeth of a ratchet I15, which is fixed to the takeupspool MI and which will be actuated by the pawl when the spring I12moves the lever I10 into engagement with the pm Hi. The lever I10 isactuated each time the actuating handle 38 is operated through one.complete cycle due to the fact that the cam 31 will rock the lever I IIin a counter-clockwise direction to thereby move the block H4 and plateI downwardly shown in Fig. 4, the blocks H4 and plate I39, in

moving upwardly, will disengage the lever I10 from the abutment I80 andthe spring I12 will, thereby, cause the pawl I13 to step the takeupspool I4I a short distance to carry a new supply of typewriter ribboninto engagement with the marking element I35.

Fixed to the actuating arm 29 is a block I90 having a pin I9I extendingtherefrom on which there is pivoted a trip pawl I92. The trip pawl, inits normal position, as shown in Fig. 1, rests on a pin I93 and when theactuating arm 29 is moved downwardly, the pawl I92 will engage abent-over portion of a contact member I94 and will rock about the pin I9I. A pin I95 is provided to prevent the pawl I92 from moving in acounterclockwise direction about its pivot pin I9! beyond apredetermined distance, When the actuating arm 29 is moved upwardly, thepawl I92 resting on the pin I93 will engage the bent-over portion of thecontact member I94 and move a contact I96 mounted on the contact memberI94 into engagement with a contact spring I91. When the contact I96engages the contact spring I91, both of which are insulatedly mounted ona bracket I98, a circuit will be completed between the leads I99 and 299connected to the contact members I94 and I91, respectively,-to energizethe solenoid I 34. The coil formed by the portions II and I4 ofthe-split coil is interrupted so that there is, in efiect, provided twoseparate coils, which, in Fig. 2, have been designated 200 and 20L Thecoil 200 includes those parts of the portions II and I4 which lie onone-half of the semi-circle and the coil 20I includes those parts of theportions I I and I4 which lie on the other half of the semicircle. Thecoils 200 and 20I thus formed are, as shown in Fig. 2, connected in abridge circuit, which includes the coil 200 in one arm, the coil 20I inthe second arm, resistance 202 in a third arm, and a resistance 203 ofequal value in the fourth arm. A source of current 204 is connectedthrough a transformer 205 to the points 206 and 201 of the bridgecircuit thus formed and an amplifier 208, whose output is connected to amilliammeter 209, is connected through a suitable transformer 2 I0 tothe points 2| 1 and 2I2 of the bridge circuit. It is believed to beapparent that when a core is placed in the apparatus describedhereinbefore and the portions H and I4 of the split coilsinterconnected, the core will change the relative impedance of thebridge circuit shown in Fig. 2 and the milliammeter will be deflectedfrom its normal position an amount dependent upon the variation betweenthe two halves of the core at that time associated with the coils 200and20L A better understanding of the invention will be had by the followingbrief description of the mode of operation thereof. The core to betested may be placed on the shoulder 93 and the handle out of the pathof the portion I4 of the split coil.

As soon as the cam 31 has thus moved the block H4 and apparatus carriedthereby out of the path'of the portion I4 of the split coil, the arm.29will engage the shoulder on the pin 91 and move the disc and ring 92downwardly to and .carry the ring 90 down onto the turn table I00.

As the rack 30 moves downwardly, the springpressed shouldered members 58will engage with their respective contactors I58 and the springpressedshouldered members 56 will engage with their respective contact members82 and 06 to complete the coils 200 and 20I surrounding the core 94.After the core 94 has thus been carried down into position within thecoils 200 and 20I, it may be rotated by rotating the dial or hand wheelI05 until a balance or approximately balanced condition is indicated bythe milliammeter 209. When this condition is indicated by themilliammeter 209, the handle 38 may be returned to its normal position.As the handle 38 returns to its normal position, the portion I4 of thesplit coil will be moved upwardly through the action of the rack andpinion 30 and 3| and the actuating arm 29 will move upwardly along theshouldered pin 91 until the actuating arm 29 engages the disc 93 withoutmoving the core 94 from the testing position. As soon as the actuatingarm 29 engages the disc 96, it will move the disc 96 upwardly to carrythe ring 92 with it and shortly after the ring 92 moves out of itslowermost position, it will engage the shoulder 9I on the ring 90 tocarry the core up and into the position shown in Fig. 3. As the coremoves into the position shown in Fig. 3, the cam 31 will have its lowportion moved into association with the cam roller H3 and the springsI22 and I23 will be permitted to move the block II4 to the positionshown in Fig. 4. As soon as the block II I arrives in the position shownin Fig. 4, the trip pawl I92 will engage the contact member I94 tocomplete a circuit to the solenoid I34, thereby to energize the solenoidand cause the marking element I35 to drive the typewriter ribbon I42against the periphery of the core. As soon as the coils 208 and 2M aresplit along a line adjacent the marking element I35, the mark impressedon the core by the marking element I35 will indicate the point at whichseparators should be put on the core to divide the core in two equalhalves, so that when coils are wound on the core, equal windings on eachhalf of the core will cause the coils to have substantially equalinductance when connected in a telephone circuit.

Although a specific embodiment of the invention has been describedhereinbefore, it will be understood that adaptations and modificationsmay be made without departing from the scope of the invention, which isto be limited only by the appended claims.

What is claimed is:

1. In a testing apparatus, a pair of semi-circular coils each split intotwo portions, means for moving the split portions of said coils togetherto form a pair of coils, and means for rotating an article within thecoils.

2. In a testing apparatus for annular cores, a pair of semi-circularcoils, each of said coils being split into two portions, means formoving the split portions of said coils relative one to another tosurround a core to be tested, and means for rotating the core while itis surrounded by said coils.

3. In a testing apparatus for annular cores, a pair of semi-circularcoils, each of said coils being split into two portions, an arm forsupporting a portion of both coils, means for moving said arm to movethe portions of the coils carried thereby into electrical contact withthe other portions of the coils to surround a core, means for supportinga core, and means interconnecting the core supporting means and said armto carry the core into testing position upon actuation of said arm.

4. In a testing apparatus, a core receiving member, means for rotatingthe core receiving member, a pair of split coils, means for rigidlysupporting a portion of each of said coils, movable supporting means forthe other portions of said coils, and means for actuating the movablesupporting means for the coils and for moving the core receiving memberat an angle to its plane of rotation.

5. In a testing apparatus for cores, a core receiving member, a pair ofsplit coils each having movable and fixed portions, means for movingsaid core receiving member into association with the fixed portion ofthe coils, and a common actuating means for actuating the said movingmeans and for moving the movable portions of the coils into operativeengagement with the fixed portions thereof.

6. In a testing apparatus, a pair of split coils each having a fixed anda movable portion, means for rotatably supporting an article to betested within said coils, means for moving the movable portions of thecoils into operative association with the fixed portions thereof, meansfor moving the core to be tested into and out of operative associationwith the split coils, means for actuating the movable portions of thecoils, and the core moving means, and means operable under control ofsaid actuating means for marking the cores after they have beenassociated with the split coils.

7. In a testing apparatus for toroidal cores, means for rotating a core,means for measuring the relative reluctance of diametrically opposedhalves of the core, means for moving the core into and out of operativeassociation with the measuring means, and means operable under controlof said last mentioned means for marking the core on a line betweenhalves thereof which have substantially equal reluctance.

8. In a testing apparatus, a pair of coils, each of said coils beingsplit into two portions, means for moving the split portions of saidcoils together to surround an article, and means for rotating thearticle while surrounded by the coils to present various areas of thearticle to various areas of the coils.

JASPER L. BRUBAKER. FRANK J. LENGVENIS.

